The manufacture of castings for internal combustion engines poses difficult manufacturing problems. For example, the manufacture of a V-block for an internal combustion engine frequently requires that large and unwieldy cores be placed together in a sub-assembly, which is then assembled with another core or placed in a casting mold. In one such operation, the water jacket core and slab core for casting a V-block engine must be assembled into a “jacket and slab” sub-assembly that is subsequently assembled in its entirety into a crankcase core. Because of their weight and size, the water jacket core and slab core of the “jacket and slab” sub-assembly are frequently separated and broken in handling, or are damaged since the cores are fragile and easily broken. These mishaps require production delays in which the production line is frequently stopped so that the broken or damaged cores can be removed.
In the past, adhesive and/or screws have been used to fasten core elements together to maintain the integrity of the core assembly during its handling and during pouring of the casting. The use of an adhesive requires an adhesive that can be easily spread on the core elements, that will set within the shortest possible time; that will hold the core elements together as one piece and maintain their position during the casting process, and that may be removed from the casting after the casting metal solidifies. This method results in substantial costs and opportunities for unreliable castings because of a potentially unreliable interface between the core elements. The adhesive materials may separate or otherwise become degraded in storage. It is also necessary that workmen apply the adhesive correctly so that the adhesive reliably maintains the core elements together during casting and is not spread onto an exposed casting surface. Furthermore, this method requires time for applying the adhesive, assembling the core elements together and allowing the adhesive to set before the core elements can be used for casting, and it introduces into the mold an unnecessary foreign element in the form of an adhesive that may evolve gas that may become trapped in the solidified casting and cause areas of possible failure. Because of the difficulties of using adhesive to fasten core elements together, screws have been used to fasten the core elements of core assemblies together. The use of screws requires the installation of accurately sized pins in the mold-form for the core to provide accurately sized holes in the core to accept the screws. Such pins in the mold-form became eroded by the abrasive core sand and bent in use, resulting in holes in the core that are too small or that cannot accept screws from an automatic installation station. As a result, screws frequently fail to properly engage the core sand core elements and to provide holding engagement of the core sand element as a result of core sand stripping during their installation.
Neither adhesive nor screws can satisfactorily fasten together assemblies of core elements, such as water jacket core, and slab cores for V-blocks of internal combustion engines.